Questions arising from research priorities related to pathogen vectors and pathways.

Research priority

Research questions

1.1. Pathogen fates: barren vs. vegetated systems.

Vegetated zones capture and infiltrate more coliforms than bare soils, but how do different soil, pathogen, and vegetation types contribute to pathogen capture and infiltration (Roodsari et al., 2005) and can this reduce ground water quality (Thiagarajan et al., 2007)?

Though most available data are derived from controlled environments, E. coli O157:H7 appear able to survive from seedling stage to harvest under field conditions (Islam et al., 2004). How can the total influence of the many separate variables associated with field conditions best be applied to predict pathogen survival (Delaquis et al., 2007)? Are there agronomic practices that can improve sanitizer efficiencies post-harvest (Fonseca, 2006)?

Questions arising from research priorities related to mitigation and management practices.

Research priority

Research questions

2.1. Pathogens fates: after capture with management practices (MPs).

A broadly stated priority. See Priorities 1.1, 1.4, 1.5, 2.2, and 2.4. Also, what is the likely fate of pathogens excreted within MPs by fauna that are visiting or inhabiting them? Can MP choices apply evolutionary pressures to pathogens that increase their persistence and their virulence (Walther and Ewald, 2004)?

Water reuse guidelines call for undetectable levels of viable pathogens in irrigation water applied to fresh vegetables, but what information is needed as to the presence and variability of human pathogens in tailwater to develop a risk-based approach for determining when or how testing should be conducted (Hamilton et al., 2006; Mena, 2006; USEPA and U.S. AID, 2004)? How should standards be adjusted to account for different irrigation methods (Bernstein et al., 2007; Bihn and Gravani, 2006)?

What manure properties, such as pH or fiber content, may contribute to pathogen persistence (Franz et al., 2005)? How much time is needed between a manure applications and harvests under specific management conditions (Bihn and Gravani, 2006)? Composting inactivates pathogens (Larney et al., 2003), but what industry quality control standards are needed to assure proper heating and avoid cross-contamination (Wichuk and McCartney, 2007)?